1. Field of the Invention
The present invention relates to a vehicular meter unit. The present invention also relates to a display device that switches a display of a display panel, in which multiple pixels are formed in a matrix shape, between a display image and a contraction image indicating the same information.
2. Description of Related Art
A meter is installed in a cockpit for a vehicle (particularly for an automobile) for displaying vehicle speed, engine rotation speed and the like. A classical analog mechanical pointer type meter is known as such the meter. Also, a meter unit that is constructed of a display such as a liquid crystal panel and that displays a color image of the meter (so-called software meter) therein instead of the conventional analog mechanical meter, e.g., as described in Patent document 1 (JP-A-2004-182092), is widely used. Such the meter unit has an advantage of capability of easily displaying a synthesized image window such as a night vision (i.e., a night view image) provided by an infrared camera, a camera image such as a back monitor image or a map image of a car navigation system on a display screen together with the software meter.
In the case where a vehicle speed meter or a tachometer is constructed of a pointer type meter, the vehicle speed or the engine rotation speed can be directly read from a pointer position. Thus, the pointer type meter provides an advantage of intuitive recognition of the current meter indication value. However, the pointer type meter has a disadvantage that reading accuracy of the indication value is inferior to that of a digital meter directly displaying the indication value in figures. Patent document 1 describes a scheme of combining the pointer type meter and the digital meter to compensate the disadvantages with each other.
In the case where the image window such as the camera image or the map image is displayed on the display for displaying the meter, the meter is required to be displayed in a margin of the image window, so the display of the meter tends to be restricted. Therefore, Patent document 1 describes a scheme of switching the display mode between a first display mode and a second display mode. The first display mode prioritizes the meter display by omitting the display of the image window. The second display mode displays the meter image in the margin of the image window in the restricted manner by omitting or contracting the display of some meters.
FIG. 5 of Patent document 1 shows a construction of a display form in the first display mode of arranging a circular pointer type analog speed meter and a tachometer of the same type side by side (in a horizontal direction) and of locating a digital speed meter displaying the speed in figures in a central position between the speed meter and the tachometer. FIG. 6 of Patent document 1 shows a construction of a display form in the second display mode of locating an image window of a car navigation system in the center of the screen and of locating the pointer type analog speed meter and the tachometer respectively in margins on both sides of the image window. However, this construction causes following defects (1) to (3) when the display mode is switched from the first display mode to the second display mode, for example.
(1) The digital speed meter displayed in the center of the screen in the first display mode is vanished by the image window (subsidiary information output section) as soon as the display mode is switched from the first display mode to the second display mode. Therefore, there is a possibility that a driver driving the vehicle while watching the digital speed meter loses the sight of the digital speed meter and feels confused.
(2) The pointer type analog speed meter and the tachometer are displayed in sufficient spaces extending to the vicinity of the center of the screen in the first display mode. However, in the second display mode, the pointer type analog speed meter and the tachometer are displayed in compressed and deformed elliptic shapes in the margins on the both sides of the image window (subsidiary information output section) as positions largely moved from those of the first display mode. Since the form and the position of the pointer type analog speed meter change at the same time when the display mode is switched to the second display mode, there is a possibility that the driver driving the vehicle while watching the pointer type analog speed meter needs some time to recognize that the pointer type analog speed meter in the second display mode is functionally equivalent to the pointer type analog speed meter in the first display mode and feels confused.
(3) For solving the above problem (1), FIG. 26 of Patent document 1 shows a construction of continuously displaying the digital speed meter also in the second display mode in a different position on the screen (specifically, in a lower position in the left end of the screen). However, also in this case, the digital speed meter still disappears from the center of the screen in the second display mode. Therefore, there is a possibility that the driver needs some time to recognize that the display of the digital speed meter is continued in the position moved to the left end of the screen. Moreover, in the case where the digital speed meter is displayed over the deformed pointer type analog speed meter, there is a disadvantage of difficulty in reading the digital speed meter.
Patent document 2 (JP-A-H9-123848) describes a display device that switches a display of a display panel such as a liquid crystal panel, in which multiple pixels are formed in a matrix shape, between a display image and a contraction image indicating the same information. Although not clearly mentioned in Patent document 2, it is required to display a contraction image contracted in a form different from that of the display image when the display image indicating certain information is displayed in a contracted manner. It is because recognition becomes difficult if the display image is contracted in homogenous deformation and displayed without altering the form. Accordingly, it is required to contract the display image by altering the form to enable the recognition.
Therefore, when the display is switched from the display image to the contraction image, an image change as an addition of the change due to the contraction and the change due to the alteration of the form gives an odd feeling to a viewer as a rapid change of the image. This problem occurs also when the display is switched from the contraction image to the display image.